Coating compositions comprising polyureas are used in a wide variety of industries such as automotive, watercraft, aircraft, industrial, construction, military, recreational equipment including sports equipment and the like. In these industries, considerable efforts have been made to develop coating compositions that will impart the desired properties to the substrate or article being coated. For example, coatings are used to protect against damage due to corrosion, abrasion, impact, chemicals, ultraviolet light, flame, heat, and/or other environmental exposure. In addition to any of these functional properties, coatings can also be used for decorative purposes.
Sulfur-containing compounds are known to be well suited for use in aerospace sealants due to their fuel resistant nature upon crosslinking. For example, polysulfide sealants can offer high tensile strength, high tear strength, thermal resistance and resistance to high ultraviolet light. Such sealants can also offer resistance to fuel and maintain their adhesion upon exposure to fuel.
Polyureas are generally formed by reacting amines and isocyanates. The use of amines such as polyamines as crosslinkers or “curatives” is well known. For example, amines are known to crosslink with isocyanates to form urea compounds. Similarly, sulfur-containing compounds are known to crosslink with isocyanates to form thiourea compounds. The use of sulfur-containing compounds in a polyurea coating, however, has been difficult due to the high viscosity and odor of the sulfur-containing compounds. Combinations, however, would be desirable to provide optimum properties.